Since you sanded it with a 100 grit, you can go to a higher grit slowly getting rid of the scratches. I believe you can gradually go to a higher grit to a 1000. Then use metal polish.
For the dents you can take it to a body shop, and have them pull out the dents. I believe they spot weld metal rods on it, and connect it to a dent puller. I'm sorry I'm no paint, and body genius. Hope this helps man, and keep me posted on your project! Sounds cool as hell.